[Greenbuilding] basement insulation

[Paul Newby]

Keith Winston wrote:
> First, I'd say making sure you've addressed exterior moisture issues,
> if they exist, is the most important step. Then, I'd agree that you
> want to hold interior humidity levels down for several reasons. A
> dehumidifier can be a reasonable way to do that. Finally, I'd go with
> higher permeability rather than lower, especially if you're using
> spray foam: the issue of providing an air barrier is addressed by the
> foam either way. If you hold your framing off the wall, you can spray
> behind/around it, thereby reducing bridging & leakage issues.

Yes, that's pretty much the plan.  In this particular instance, there
aren't any apparent water problems.  House is at the top of a hill, good
slope and sandy soil, so it seems to be high and dry.  But I was
curious about the general case...

Bob Klahn wrote:
> In addition to Keith's advice, check out the page195 (p.194 for an
> existing basement)of the Joe Lstiburek's Builder's Guide to Cold
> Climates (EEBA on-line bookstore) for a design to allow
> weepage/condensation drainage from the inside surface of the
> foundation wall to the subslab drainage.  It also involves a small
> air gap/drain plane between the foundation wall and the finished
> wall.  

That seems like good insurance.  The woven wire sheets used for
siding underlayer seem like they should be good for this purpose.
I'll look up the reference.

Many thanks for the input, folks...

Paul N.